Cropping systems can produce food, fuel, and other benefits

By Iowa State University | February 07, 2014

Cropping systems that are profitable for farmers and balance societal needs for food, feed, fuel, energy and clean air and water are the focus and challenge of Iowa State University’s Landscape Biomass Project.

“My dad always said there is no reason that driving your car should not make the air cleaner, and there’s no reason that you should have to feel bad about turning on a light bulb,” said Emily Heaton, who grew up on a farm in central Illinois and is an assistant agronomy professor at Iowa State.

Her father’s declarations launched an investigative journey that eventually led to a research and extension appointment at Iowa State, focused on dedicated energy crops. She is one of 12 principal investigators on the project.

Ethanol made from corn kernels, a first-generation biofuels feedstock, accounts for more than 90 percent of U.S. biofuel production. Congress has mandated that second generation feedstocks be non-food biomass and be an increasing portion of the U.S. biofuel feedstock.

Heaton and others are studying how to strategically integrate second generation bioenergy crops, such as triticale, switchgrass and trees, with food and feed crops to provide marketable products as well as ecosystem services. Highly erodible, sloped fields could be planted, for example, with the deep-rooted bioenergy crops.

Researchers on the project are assessing the amount of variation in grain yields, biomass yields, soil moisture and soil water quality among various cropping systems and landscape positions. A journal article detailing the findings of the group’s research to-date is available online here.

“My father was absolutely right,” Heaton said. “If you are using biofuels developed from perennial plants like switchgrass, which can store five times more biomass below ground than they do above ground, every time you drive your car you’re virtually scrubbing carbon out of the air.”

For every molecule of CO2 taken out of the air to make biomass, which you combust or in some way put back in the air when you use bioenergy, more have been stored underground, said Heaton. The carbon stored underground will move through the carbon cycle through the soil, contributing to soil organic matter.

“Some of it’s going to eventually get respired back to the atmosphere, but you’re going to build soil and store carbon below ground as you do it. Thereby you could be contributing to making the planet cleaner every time you drive your car and turn on the air conditioner,” Heaton said.

Deep-rooted perennials, like switchgrass and trees, also hold soils in place even after harvesting and, depending on their placement in a cropping system, can take up excess nutrients that might otherwise run off into surface and sub-surface water.

The Landscape Biomass Project analyzes data from five novel cropping systems which are planted on a hillside, at the Iowa State Uthe Research Farm located in central Iowa. At the bottom of the hillside is a stream that eventually flows into Big Creek Lake.

“It might seem like this project is nothing new, but actually it’s quite new because all of the agronomic and environmental research to date has been on flat homogenous land,” Heaton said.

Project researchers found that the more diversified the cropping system, the more stable or even increasing crop yields are.

“That’s despite the extreme climate variability we had in the four-year period of 2009 to 2012,” Heaton said. “These findings suggest why diversity used to be more integral to crop management when more people owned their farmland and when they had more control over the markets for their crops.”

The profitability of the five cropping systems also was analyzed. Of the five systems studied, the continuous corn cropping system was most profitable under current market conditions, followed by a corn-soybean rotation that incorporated triticale as a cover crop every third year and a corn-switchgrass system. A triticale-hybrid aspen intercropping system had the highest yields over the long term, but was not profitable under foreseeable market values.

Heaton said these results demonstrate the need for markets and other infrastructure to support advanced bioenergy crop growers.

“There’s no crop insurance for these new crops. Your coop doesn’t know how to help you. People should not assume that farmers don’t want to do anything other than grow corn. It’s not true. In fact, it’s usually farmers who are most open to change. They are the ones reaching out to ask how they can make this work economically. But farmers are constrained by policy, by what they need to do to make a living in a given year,” Heaton said.

She said future plans for project outreach include educating policy makers and continued cropping systems research will help answer farmers’ questions in the future.

“Our job is to figure out how to tell farmers to grow bioenergy crops on marginal land. We want to get all the research questions answered so that when we do have policies and markets that support diversification of farm systems, we can give good recommendations.”

Heaton said her “ultimate goal” is to go back to Illinois to grow bioenergy crops on her parents’ land.

“I have all these questions that come from my dad and mom. That’s my job now — getting those questions answered. I’d love to get back to the farm. But first I have to make this all work economically.”